System and method for determining state of charge for an electric energy storage device

Patent metadata

Field	Value
Publication number	US-2023216072-A1
Application number	US-202318182892-A
Country	US
Kind code	A1
Filing date	Mar 13, 2023
Priority date	Nov 2, 2018
Publication date	Jul 6, 2023
Grant date	—

Abstract

Systems and methods for operating an electric energy storage device are described. The systems and methods may generate a state of charge estimate that is based on negative electrode plating. An overall state of charge may be determined from the state of charge estimate that is based on negative electrode plating and a state of charge estimate that is not based on negative electrode plating.

First claim

1 . A method, comprising:
operating an iron flow electric energy storage cell stack of N electric energy storage cell stacks; determining a state of charge based on negative electrolyte based on a parameter indicative of plating efficiency at a negative electrode, the parameter further indicating a capacity of the iron flow electric energy storage cell stack to source and sink current; in response to the iron flow electric energy storage cell stack changing from charging to discharging or in response to the iron flow electric energy storage cell stack changing from discharging to charging, decoupling the iron flow electric energy storage cell stack from the N electric energy storage cell stacks to determine an open circuit voltage of the iron flow electric energy storage cell stack; and determining an adjusted state of charge based on the determined open circuit voltage.

2 . The method of claim 1 , further comprising determining a state of charge of based on open circuit voltage based on the determined open circuit voltage of the iron flow electric energy storage cell stack.

3 . The method of claim 2 , further comprising determining a state of charge based on positive electrolyte based on a total shunt current of a positive electrolyte of the iron flow electric energy storage cell stack over a time interval.

4 . The method of claim 3 , further comprising determining if a state of charged based on electrolyte is within a percentage of the state of charge based on open circuit voltage, wherein the state of charge based on electrolyte is equivalent to the state of charge based on positive electrolyte or the state of charge based on negative electrolyte.

5 . The method of claim 4 , wherein determining the adjusted state of charge occurs in response to determining the state of charge based on open circuit voltage is within the percentage of the state of charge based on electrolyte.

6 . The method of claim 4 , further comprising in response to determining the state of charge based on electrolyte is not within the percentage of the state of charge based on open circuit voltage, performing mitigating actions.

7 . The method of claim 6 , wherein mitigating actions include cleansing the iron flow electric energy storage cell stack.

8 . The method of claim 1 , wherein determining the adjusted state of charge of the iron flow electric energy storage cell stack includes dividing the state of charge based on electrolyte by the state of charge based on open circuit voltage.

9 . A method for operating an iron flow electrical energy storage cell stack, comprising:
determining a state of charge based on open circuit voltage in response the iron flow electrical energy storage cell stack changing from charging to discharging or in response to the iron flow electrical energy storage cell stack changing from discharging to charging; determining a state of charge based on electrolyte; and adjusting operation of the iron flow electrical energy storage cell stack via a controller according to a result of comparing the state of charge based on the electrolyte and the state of charge based on open circuit voltage, wherein the iron flow electrical energy storage cell stack includes a negative electrolyte tank and a positive electrolyte tank.

10 . The method of claim 9 , wherein determining the state of charge based on electrolyte further includes comparing a state of charge based on negative electrolyte to a state of charge based on positive electrolyte.

11 . The method of claim 10 , wherein comparing the state of charge based on negative electrolyte to the state of charge based on positive electrolyte includes determining a minimum value when the iron flow electrical energy storage cell stack is discharging.

12 . The method of claim 10 , wherein comparing the state of charge based on negative electrolyte to the state of charge based on positive electrolyte includes determining a maximum value when the iron flow electrical energy storage cell stack is charging.

13 . The method of claim 9 , wherein adjusting operation of the iron flow electrical energy storage cell stack includes performing mitigating actions when the result of comparing the state of charge based on electrolyte to the state of charge based on open circuit voltage is the state of charge based on electrolyte is not within a percentage of the state of charge based on open circuit voltage.

14 . The method of claim 9 , wherein adjusting operation of the iron flow electrical energy storage cell stack includes determining a state of charge adjustment factor when the result of comparing the state of charge based on electrolyte to the state of charge based on open circuit voltage is the state of charge based on electrolyte is within a percentage of the state of charge based on open circuit voltage.

15 . An electric power system, comprising:
an iron flow electric energy storage cell stack including a positive electrode and a negative electrode, the positive electrode in physical communication with a first electrolyte that is stored in a first tank of the electric power system and the negative electrode in physical communication with a second electrolyte that is stored in a second tank of the electric power system; and a controller including executable instructions stored in non-transitory memory to decouple the iron flow electric energy storage cell stack from the electric power system in response to the iron flow electric energy storage cell stack changing from charging to discharging or in response to the iron flow electric energy storage cell stack changing from discharging to charging.

16 . The electric power system of claim 15 , wherein the executable instructions to decouple the iron flow electric energy storage cell stack from the electric power system further includes to open a contactor.

17 . The electric power system of claim 15 , wherein the executable instructions to decouple the iron flow electric energy storage cell stack from the electric power system for at least 30 seconds.

18 . The electric power system of claim 15 , wherein the executable instructions further include to determine a state of charge based on open circuit voltage after the iron flow electric energy storage cell stack is decoupled from the electric power system.

19 . The electric power system of claim 18 , wherein the executable instructions to determine the state of charge based on open circuit voltage include to use a function that relates state of charge based on open circuit voltage to the open circuit voltage of the iron flow electric energy storage cell stack.

20 . The electric power system of claim 19 , wherein the executable instructions further include to determine a state of charge adjustment factor based on the state of charge based on open circuit voltage.

Assignees

• Ess Technology Inc

Inventors

• Song Yang
• Mcdonald Timothy J
• Groberg Thiago

Classifications

• H01M8/04582

  of the individual fuel cell · CPC title

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/04611 Primary

  of the individual fuel cell · CPC title

• H01M8/04932

  of the individual fuel cell · CPC title

• H01M8/04955

  Shut-off or shut-down of fuel cells · CPC title